I ordered new door lock cylinders from Majestic Honda, and ended up getting more than I expected:

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/diy-fixing-doorlocks-open-any-key-2237857/

I thought it would just be the tumbler and cylinder, not the whole assy with keys and all. I'm guessing I just swap the numbered lock plates from my existing cylinders into the new ones?

 

Yes. You want to be careful when you are disassembling the locks, because you need to know what order the lock plates are in so you rebuild it correctly. The plates are spring loaded. Both the plates and springs can go flying if you're not careful. Disassemble slowly. Write down the order and orientation of the lock plates.

Hopefully you have enough of each lock plate # to rebuild your old locks.

 

Is there some reason I couldn't use the ones from the old locks? I figured I could clean them up and re-use them.

 

I misunderstood. It seems that usually people rebuild door locks because the old lock plates are worn and the key no longer can operate the lock. But yes the cylinders can just as easily wear and so fail, too.

If the old lock plates are fine, then yes you can re-use them.

 

Well, hopefully that's the case, I really don't know what's wrong with them. I'm guessing the only way you can get new lock plates is by buying more cylinders? Is it obvious to see if they're usable?

 

Can you clarify what is wrong with the old locks?

If the locks are not working, it could be the lock plates (also known as "tumbler pins"), the cylinder, the key, or both. All of these are subject to wear. Having to re-build them after ten years or so (or after some yo-yo broke into your car) is usual. It makes sense to replace both the cylinder and tumbler pins, to maximize reliability in the coming years.

An alternative is to examine the old lock closely and see what part is failing. Old locks do restore nicely sometimes with just a good cleaning. Use something like PB Blaster to clean off the old, grimy lubricant. Wipe all parts off. Re-lube with a little lithium grease.

If parts clearly are worn, go to the junkyard and salvage the lock parts you think you need. I did this a couple years ago for my 93 Civic and got myself good-enough working locks that matched up fine with my ignition key.

Here's a poor person's approach: Sometimes just removing the faulty lock plate will give you a lock that works fine. But it is not as safe as having all lock plates intact.

OTOH what you bought from Majestic ran about $30 per lock, right? For a whole new lock with non-worn parts, this does not seem too bad, compared to the sweat labor of a trip to the junkyard to get a handful of possibly worn lock parts.

The thread you linked in your first post is a perfectly good how-to. The lock plate setup is just a bit different in appearance on the 01-05 Civics.